The fallback image tries to load the normal image but if that fails it'll take over and continue with the fallback image.
So I am guessing the 2 images are the same. Then why 2 exact the same image? In case of damaged flash area?
I am asking this because I want to embed a linux kernel in the BIOS rom to run Flash_and_Burn util (For convenience when updating Bios). There probably won't be enough ROM space if I use both images.